Calcium channel inhibitors (CCI's) are thought to affect calcium flux through membrane bound channels as their major site of action. There are reports of clinical trials involving over 150 patients suggesting that CCI's also have beneficial effects in neuropsychiatric disorders. There are four major subclasses of CCI's; each appears to have unique combinations of biochemical and behavioral properties. Additional studies have suggested a complex interaction between dopamine receptor function and calcium channels. We have completed a study of the clinical effects of verapamil in a schizophrenic population where trends toward improvement did not reach statistical significance. We have proceeded with the protocol to examine the effects of nifedipine in a similar cohort. Results on the first eight completed subjects have shown two trends: 1) an increase in "negative" symptoms of schizophrenia while on active nifedipine, and 2) a decrease in abnormal involuntary movements on the AIMS (abnormal involuntary movement scale) while on active nifedipine. Also, a comparison of the placebo periods before and after active nifedipine suggests a significant sequence effect measured by continued worsening of the BPRS (brief psychiatric rating scale) scores after active nifedipine.